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	$184.98	6.401%	$196.8206	$196.82	$196.80	$196.80
Purchase #2	$27.41	6.483%	$29.187	$29.19	$29.20	$29.20
Purchase #3	$78.38	6.451%	$83.4363	$83.44	$83.45	$83.40
Purchase #4	$89.51	13.433%	$101.5339	$101.53	$101.55	$101.50
Purchase #5	$249.43	7.498%	$268.1323	$268.13	$268.15	$268.10
Purchase #6	$184.34	13.110%	$208.507	$208.51	$208.50	$208.50
Purchase #7	$104.44	13.654%	$118.7002	$118.70	$118.70	$118.70
7 purchase totals =	$918.49		$1,006.3173	$1,006.32	$1,006.35	$1,006.20