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	$146.88	3.643%	$152.2308	$152.23	$152.25	$152.20
Purchase #2	$162.52	7.319%	$174.4148	$174.41	$174.40	$174.40
Purchase #3	$181.48	6.551%	$193.3688	$193.37	$193.35	$193.40
Purchase #4	$78.84	11.772%	$88.121	$88.12	$88.10	$88.10
Purchase #5	$94.35	6.553%	$100.5328	$100.53	$100.55	$100.50
Purchase #6	$193.25	4.860%	$202.642	$202.64	$202.65	$202.60
Purchase #7	$96.40	4.674%	$100.9057	$100.91	$100.90	$100.90
7 purchase totals =	$953.72		$1,012.2159	$1,012.21	$1,012.20	$1,012.10