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	$193.54	4.528%	$202.3035	$202.30	$202.30	$202.30
Purchase #2	$114.48	12.454%	$128.7373	$128.74	$128.75	$128.70
Purchase #3	$31.94	5.241%	$33.614	$33.61	$33.60	$33.60
Purchase #4	$236.47	9.418%	$258.7407	$258.74	$258.75	$258.70
Purchase #5	$50.71	12.198%	$56.8956	$56.90	$56.90	$56.90
Purchase #6	$191.76	12.781%	$216.2688	$216.27	$216.25	$216.30
Purchase #7	$177.83	4.217%	$185.3291	$185.33	$185.35	$185.30
7 purchase totals =	$996.73		$1,081.8890	$1,081.89	$1,081.90	$1,081.80