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	$85.95	4.245%	$89.5986	$89.60	$89.60	$89.60
Purchase #2	$212.96	4.295%	$222.1066	$222.11	$222.10	$222.10
Purchase #3	$147.33	4.470%	$153.9157	$153.92	$153.90	$153.90
Purchase #4	$180.50	4.654%	$188.9005	$188.90	$188.90	$188.90
Purchase #5	$191.80	3.322%	$198.1716	$198.17	$198.15	$198.20
Purchase #6	$139.43	6.615%	$148.6533	$148.65	$148.65	$148.70
Purchase #7	$160.82	8.510%	$174.5058	$174.51	$174.50	$174.50
7 purchase totals =	$1,118.79		$1,175.8521	$1,175.86	$1,175.80	$1,175.90