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	$225.86	4.789%	$236.6764	$236.68	$236.70	$236.70
Purchase #2	$65.64	10.160%	$72.309	$72.31	$72.30	$72.30
Purchase #3	$173.89	4.451%	$181.6298	$181.63	$181.65	$181.60
Purchase #4	$172.88	6.494%	$184.1068	$184.11	$184.10	$184.10
Purchase #5	$181.27	9.401%	$198.3112	$198.31	$198.30	$198.30
Purchase #6	$88.84	3.399%	$91.8597	$91.86	$91.85	$91.90
Purchase #7	$42.52	9.614%	$46.6079	$46.61	$46.60	$46.60
7 purchase totals =	$950.90		$1,011.5008	$1,011.51	$1,011.50	$1,011.50