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	$182.54	5.272%	$192.1635	$192.16	$192.15	$192.20
Purchase #2	$150.65	9.642%	$165.1757	$165.18	$165.20	$165.20
Purchase #3	$54.57	10.554%	$60.3293	$60.33	$60.35	$60.30
Purchase #4	$31.60	5.494%	$33.3361	$33.34	$33.35	$33.30
Purchase #5	$178.27	7.264%	$191.2195	$191.22	$191.20	$191.20
Purchase #6	$95.93	9.481%	$105.0251	$105.03	$105.05	$105.00
Purchase #7	$242.34	13.605%	$275.3104	$275.31	$275.30	$275.30
7 purchase totals =	$935.90		$1,022.5596	$1,022.57	$1,022.60	$1,022.50