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	$203.26	3.549%	$210.4737	$210.47	$210.45	$210.50
Purchase #2	$74.73	4.250%	$77.906	$77.91	$77.90	$77.90
Purchase #3	$227.46	3.711%	$235.901	$235.90	$235.90	$235.90
Purchase #4	$165.76	13.814%	$188.6581	$188.66	$188.65	$188.70
Purchase #5	$144.52	7.624%	$155.5382	$155.54	$155.55	$155.50
Purchase #6	$26.53	6.720%	$28.3128	$28.31	$28.30	$28.30
Purchase #7	$153.75	11.562%	$171.5266	$171.53	$171.55	$171.50
7 purchase totals =	$996.01		$1,068.3164	$1,068.32	$1,068.30	$1,068.30