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	$176.42	9.497%	$193.1746	$193.17	$193.15	$193.20
Purchase #2	$5.77	5.438%	$6.0838	$6.08	$6.10	$6.10
Purchase #3	$73.40	7.424%	$78.8492	$78.85	$78.85	$78.80
Purchase #4	$88.45	11.618%	$98.7261	$98.73	$98.75	$98.70
Purchase #5	$105.61	5.866%	$111.8051	$111.81	$111.80	$111.80
Purchase #6	$208.53	6.531%	$222.1491	$222.15	$222.15	$222.10
Purchase #7	$79.49	11.666%	$88.7633	$88.76	$88.75	$88.80
7 purchase totals =	$737.67		$799.5512	$799.55	$799.55	$799.50