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	$69.40	7.531%	$74.6265	$74.63	$74.65	$74.60
Purchase #2	$110.27	6.638%	$117.5897	$117.59	$117.60	$117.60
Purchase #3	$98.71	5.776%	$104.4115	$104.41	$104.40	$104.40
Purchase #4	$170.78	11.466%	$190.3616	$190.36	$190.35	$190.40
Purchase #5	$129.52	13.279%	$146.719	$146.72	$146.70	$146.70
Purchase #6	$188.26	6.503%	$200.5025	$200.50	$200.50	$200.50
Purchase #7	$168.56	12.323%	$189.3316	$189.33	$189.35	$189.30
7 purchase totals =	$935.50		$1,023.5424	$1,023.54	$1,023.55	$1,023.50