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	$100.88	4.664%	$105.585	$105.59	$105.60	$105.60
Purchase #2	$130.65	4.730%	$136.8297	$136.83	$136.85	$136.80
Purchase #3	$165.87	12.766%	$187.045	$187.05	$187.05	$187.00
Purchase #4	$93.57	7.175%	$100.2836	$100.28	$100.30	$100.30
Purchase #5	$43.32	4.143%	$45.1147	$45.11	$45.10	$45.10
Purchase #6	$156.57	4.180%	$163.1146	$163.11	$163.10	$163.10
Purchase #7	$26.48	7.769%	$28.5372	$28.54	$28.55	$28.50
7 purchase totals =	$717.34		$766.5098	$766.51	$766.55	$766.40