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	$105.90	7.281%	$113.6106	$113.61	$113.60	$113.60
Purchase #2	$197.33	7.139%	$211.4174	$211.42	$211.40	$211.40
Purchase #3	$40.81	3.592%	$42.2759	$42.28	$42.30	$42.30
Purchase #4	$40.87	10.417%	$45.1274	$45.13	$45.15	$45.10
Purchase #5	$164.63	12.454%	$185.133	$185.13	$185.15	$185.10
Purchase #6	$167.77	13.782%	$190.8921	$190.89	$190.90	$190.90
Purchase #7	$211.99	11.399%	$236.1547	$236.15	$236.15	$236.20
7 purchase totals =	$929.30		$1,024.6111	$1,024.61	$1,024.65	$1,024.60