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	$187.98	4.294%	$196.0519	$196.05	$196.05	$196.10
Purchase #2	$196.44	7.501%	$211.175	$211.18	$211.20	$211.20
Purchase #3	$27.58	3.279%	$28.4843	$28.48	$28.50	$28.50
Purchase #4	$32.43	3.130%	$33.4451	$33.45	$33.45	$33.40
Purchase #5	$234.61	12.424%	$263.7579	$263.76	$263.75	$263.80
Purchase #6	$189.31	4.868%	$198.5256	$198.53	$198.55	$198.50
Purchase #7	$137.34	5.788%	$145.2892	$145.29	$145.30	$145.30
7 purchase totals =	$1,005.69		$1,076.7290	$1,076.74	$1,076.80	$1,076.80