Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$184.39	3.731%	$191.2696	$191.27	$191.25	$191.30
Purchase #2	$141.87	7.557%	$152.5911	$152.59	$152.60	$152.60
Purchase #3	$89.77	8.435%	$97.3421	$97.34	$97.35	$97.30
Purchase #4	$190.43	13.597%	$216.3228	$216.32	$216.30	$216.30
Purchase #5	$169.69	9.459%	$185.741	$185.74	$185.75	$185.70
Purchase #6	$118.75	5.537%	$125.3252	$125.33	$125.35	$125.30
Purchase #7	$128.59	13.365%	$145.7761	$145.78	$145.80	$145.80
7 purchase totals =	$1,023.49		$1,114.3679	$1,114.37	$1,114.40	$1,114.30