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	$147.93	3.672%	$153.362	$153.36	$153.35	$153.40
Purchase #2	$40.78	11.709%	$45.5549	$45.55	$45.55	$45.60
Purchase #3	$150.28	4.191%	$156.5782	$156.58	$156.60	$156.60
Purchase #4	$18.67	10.233%	$20.5805	$20.58	$20.60	$20.60
Purchase #5	$111.33	3.120%	$114.8035	$114.80	$114.80	$114.80
Purchase #6	$42.56	7.113%	$45.5873	$45.59	$45.60	$45.60
Purchase #7	$190.86	10.172%	$210.2743	$210.27	$210.25	$210.30
7 purchase totals =	$702.41		$746.7407	$746.73	$746.75	$746.90