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	$76.27	3.515%	$78.9509	$78.95	$78.95	$79.00
Purchase #2	$22.27	13.628%	$25.305	$25.31	$25.30	$25.30
Purchase #3	$36.93	6.401%	$39.2939	$39.29	$39.30	$39.30
Purchase #4	$234.99	5.203%	$247.2165	$247.22	$247.20	$247.20
Purchase #5	$63.89	13.425%	$72.4672	$72.47	$72.45	$72.50
Purchase #6	$121.97	4.244%	$127.1464	$127.15	$127.15	$127.10
Purchase #7	$208.47	3.868%	$216.5336	$216.53	$216.55	$216.50
7 purchase totals =	$764.79		$806.9135	$806.92	$806.90	$806.90